..........................
20:2 2/15+25 5/7:1 1/35/21 7/9:4 2/3-1 20*15/32+180/7*35/36/196/9*3/14-1 300/32+6300/252/588/126-1 75600/8064+201600/8064/462/126 277200/8064/462/126=277200*126:8064*462=34927200/3725568=9 1397088/3725568=9 617/4312